24 I/O PORTS (GPIO)
24-12
Seiko Epson Corporation
S1C33L26 TECHNICAL MANUAL
Bus Drive Control Register (GPIO_BUS_DRV)
Register name Address
Bit
Name
Function
Setting
Init. R/W
Remarks
Bus Drive
Control Register
(GPIO_BUS_
DRV)
0x300320
(8 bits)
D7–2 –
reserved
–
–
–
0 when being read.
D1
LDRVDB
D[15:0] low drive
1 Low drive
0 Normal
output
0
R/W Write-protected
D0
LDRVAD
A[25:0] low drive
0
R/W
D[7:2]
Reserved
D1
LDRVDB: D[15:0] Low Drive Bit
Drives the data bus signals forcibly low.
1 (R/W): Low drive
0 (R/W): Normal output (default)
When LDRVDB is set to 1, the D[15:0] signals are forcibly driven low. When it is set to 0, the signals
are controlled by the SRAMC/SDRAMC normally.
D0
LDRVAD: A[25:0] Low Drive Bit
Drives the address bus signals forcibly low.
1 (R/W): Low drive
0 (R/W): Normal output (default)
When LDRVAD is set to 1, the A[25:0] signals are forcibly driven low. When it is set to 0, the signals
are controlled by the SRAMC/SDRAMC normally.
P
x
Port Pull-up Control Registers (GPIO_P
x
_PUP)
Register name Address
Bit
Name
Function
Setting
Init. R/W
Remarks
P
x
Port Pull-up
Control Register
(GPIO_P
x
_PUP)
0x300321
|
0x30032c
(8 bits)
D7–0 PUP
x
[7:0]
P
x
[7:0] port pull-up enable
1 Enable
0 Disable
*
R/W Write-protected
Note: The PUP
xy
bits for unavailable pins are read only bits from which 0 is always read out.
D[7:0]
PUP
x
[7:0]: P
x
[7:0] Port Pull-Up Enable Bits
Enables or disables the pull-up resistor for the I/O port pin.
1 (R/W): Enabled
0 (R/W): Disabled
PUP
xy
is the pull-up enable bit that corresponds directly to P
xy
port. Setting to 1 enables the pull-up
resistor so that the port pin will be pulled up when the port is set to input mode.
When the port is in output mode, the port pin is not pulled up even if PUP
xy
is set to 1.
The pull-up register is disabled when PUP
xy
is set to 0.
This control is also effective when the port is used for a peripheral module function.
The table below shows the initial pull-up settings.
8.2 Initial Pull-Up Status
Table 24.
Port
P
x
0
P
x
1
P
x
2
P
x
3
P
x
4
P
x
5
P
x
6
P
x
7
P0
–
–
–
–
–
–
–
–
P1
–
–
–
–
–
–
–
–
P2
–
–
P3
–
–
–
–
–
Enabled
–
P4
–
–
–
P5
–
–
–
Enabled
–
–
–
P6
Enabled
P7
–
–
–
–
–
Enabled
P8
–
–
–
–
P9
–
–
–
–
–
–
–
–
PA
–
Enabled
–
–
–
–
–
PB
–
–
–
–
–
–
–
–
PC
Pull-up resistors not included
–: Disabled